According to newly published meta-analysis data in JAMA, found here and here (note: subscription required). A write-up of the data are provided in today’s NYT. On the basis of abstracted data, here’s a quick graphic view of the rates of amyloid positivity (determined via PET imaging) in the various subgroups assessed.

With the exception of patients with AD, amyloid positivity increased with age (from 50 or 60 years to 90), regardless of clinical status; however, the amyloid burden appeared to escalate most dramatically in patients with MCI.

The amyloid burden was also greater in carriers of an APOE ε4 allele–a known risk factor for AD and brain amyloid–again, regardless of clinical dementia type.

Amyloid positivity was highest in those patients with AD, and especially in those patients who were APOE ε4 carriers. Oddly enough, however, the burden dropped with age–possibly as a result of progressive neuronal loss.

These data aren’t terribly surprising, but they reinforce the idea that PET imaging for amyloid is useful–if not crucial–in those patients with AD who enroll in trials of anti-amyloid medications. It is also important to be aware that, in patients with AD, a reduction of the amyloid burden over years may be attributable to the natural course of the disease and not necessarily an anti-amyloid compound.

N. B.–Patients assessed at 60 years of age were those with non-AD dementias.

A native East Tennessean, Barbara Martin is a formerly practicing, board-certified neurologist who received her BS (psychology, summa cum laude) and MD from Duke University before completing her postgraduate training (internship, residency, fellowship) at the Hospital of the University of Pennsylvania in Philadelphia. She has worked in academia, private practice, medical publishing, drug market research, and continuing medical education (CME). For the last 3 years, she has worked in a freelance capacity as a medical writer, analyst, and consultant. Follow Dr. Barbara Martin on Google + and Twitter.